1. Field
The invention is in the field of devices to improve the properties of fluid flowing in a passage, particularly fluids containing particles therein. The invention is also in the field of improving the flow properties of an aerosol fluid containing medications prior to inhalation of the fluid by a patient to improve the delivery of the medications through the patient air passages to the lungs.
2. State of the Art
There are many instances where it is desired to lessen turbulence in flowing fluids and create or maintain laminar flow of such fluids. For example, a large number of people suffer from respiratory diseases such as bronchitis, emphysema, and asthma. The symptoms of these diseases in many cases can be reduced by medications inhaled into the lungs by the patient. The medications are typically dispensed from a hand held aerosol dispenser into a housing through which the patient breaths to pull air with the medication droplets therein in through the mouth, down the throat, and into the lungs.
A problem with these treatments is that a major percentage of the medication is deposited in the mouth, throat, and trachea of the patient as the air travels from the mouth to the lungs. With some devices, a significant amount of the medication is also deposited in the device itself, before reaching the mouth. Thus, this medication does not reach the lungs where it is needed, but is wasted and can cause side effects as it contacts and is absorbed by the surfaces of the mouth, throat, and trachea, or as it is swallowed. In many instances, the medication dispenser is a metered dose inhaler set to deliver a specific dose of medication. However, with a major percentage of the medication not reaching the lungs, the dosing is of little value.
While this problem has been recognized in the prior art, most attempts to reduce the problem have focused on ensuring small, uniform medication droplet size (such as uniform droplets in the range of one to three microns) and better and more uniform suspension of the medication droplets in the air to be breathed into the lungs. In many cases this is done by directing the spray of medicine into a spacer or expansion chamber to allow better mixing of the medicine droplets with the air to be breathed prior to breathing of the air. The spacer or chamber also acts as a reservoir to hold the air with medicine therein until breathed by the user, thereby lessening the need for the user to coordinate spraying the medicine with the inhalation of the air containing the medicine.
Spacer devices are often hollow cylindrical, conical, or bottle shaped tubes. One end of the tube has a place where a medicine pump can be attached. The other end of the tube may or may not have a valve, and may or may not have a mask attached. Examples of various spacers or mixing chambers are shown in U.S. Pat. Nos. 4,690,332, 4,972,830, 5,435,297, 5,477,849, and 6,698,422, and the AEROCHAMBER PLUS® product is shown at www.aerochambervhc.com. While providing more uniform, small sized droplets monodispersed into the air to be breathed and providing a reservoir for the air has been found to result in more of the medication reaching the lungs, room for improvement remains.